Do you agree that it would be better if fewer of the bad-guy hackers learn how to do their bad-guy things? If so, then you should agree with me that at the very least, the title of a hacking type book that could teach someone how to crack computers shouldn't make it sound like it could teach that--rather, it should make it sound like it teaches how to prevent that from happening, so fewer bad-guy hackers would buy it. But I think I'm getting repetitive.
If you want to be morally consistent, though, you should probably also boycott everything O'Reilly's ever touched. It's a long list, though, and it includes this site.
I will be taking whatever action I deem reasonable to hurt O'Reilly. I'm not limiting it to not buying their books.